déjà vu

Déjà vu is French for "already seen." Déjà vu is an uncanny feeling or illusion of having already seen
or experienced something that is being experienced for the first time. If we assume that
the experience is actually of a remembered event, then déjà vu probably occurs
because an original experience was neither fully attended to nor elaborately encoded
in memory. If so,
then it would seem most likely that the present situation triggers the recollection of a fragment
from one's past. The experience may seem uncanny if the memory is so fragmented that no
strong connections can be made between the fragment and other memories.

Thus, the feeling that one has been there before is often due to the fact that one
has
been there before. One has simply forgotten most of the original experience because one
was not paying close attention the first time. The original experience may even have
occurred only seconds or minutes earlier.

On the other hand, the déjà vu experience may be due to having seen
pictures or heard vivid stories many years earlier. The experience may be
part of the dim recollections of childhood.

However, it is possible that the déjà vu feeling is triggered by a
neurochemical action in the brain that is not connected to any actual experience in the
past. One feels strange and identifies the feeling with a memory,
even though the experience is completely new.

The term was applied by Emile Boirac (1851-1917), who had strong interests in
psychic phenomena. Boirac's term directs our attention to the past. However, a
little reflection reveals that what is unique about déjà vu is not something from the
past but something in the present, namely, the strange feeling one has. We often have experiences
the novelty of which is unclear. In such cases we may have been led to ask
such questions as, "Have I read this book before?" "Is this an episode of Inspector Morse
I've seen before?" "This place looks familiar; have I been here before?" Yet, these
experiences are not accompanied by an uncanny feeling. We may feel a bit confused, but the
feeling associated with the déjà vu experience is not one of confusion; it
is one of
strangeness. There is nothing strange about not remembering whether you've read a book
before, especially if you are fifty years old and have read thousands of books over
your lifetime. In the déjà vu experience, however, we feel strange because we
don't think we should feel familiar with the present perception. That sense of
inappropriateness is not present when one is simply unclear whether one has read a book or
seen a film before.

Thus, it is possible that the attempt to explain the déjà vu experience in terms of
lost memory, past lives, clairvoyance,
and so on may be completely misguided. We should be
talking about the déjà vu feeling. That feeling may be caused by a brain state,
by neurochemical factors during perception that have nothing to do with memory. It is
worth noting that the déjà vu feeling is common among psychiatric patients. The déjà
vu feeling also frequently precedes temporal lobe epilepsy attacks. When Wilder
Penfield did his famous experiment in 1955 in which he electrically stimulated
the temporal lobes, he found about 8% of his subjects experienced "memories." He
assumed he elicited actual memories. They
could well have been hallucinations and the first examples of artificially stimulated
déjà vu.